You are dating a user and a guy who intends to freeload. My goodness, how you cannot see this for what it is, is rather shocking to me.
If he is going to move in and pay half of everything, then yes, put him on the lease so he is legally financially responsible for the rent. But, either way, if he defaults or leaves you or you kick him out, you are still responsible for full rent payment.
He need not be on the lease to pay half the rent. If he is there using half of the utilities and eating half of the groceries, that does not equal his rent, that equals his CONSUMPTION of those things. Two totally different things. Rent is a monthly expense for living someplace. Eating and using electricity are in ADDITION to paying rent, not IN PLACE of paying rent.
If you allow him to move in with you under his silly suggestions, then you are a fool. Don't do it.
Of course your boyfriend should pay half of the monthly expenses: half the rent, half the utilities, half the food.
Anything less than that means he is using you. But, those who are desperate for a boyfriend or fear being alone would agree to just about anything.